Fluid pump having pulsing means and money accumulator

ABSTRACT

A CONTROL AND CHANGE MAKING DEVICE IS PROVIDED FOR A FLUID DISPENSING PUMP TO RECEIVE MONEY DEPOSITED BY A CUSTOMER AND STORE INFORMATION SIGNALS INDICATIVE OF THE AMOUNT OF MONEY RECEIVED. AS FLUID IS DISPENSED, PLUS ARE PRODUCED TO REDUCE THE AMOUNT OF STORED INFORMATION SIGNALS UNTIL THE DESIRED AMOUNT OF FLUID IS DESPENSED. WHEN THE AMOUNT OF FLUID DISPENSED REPRESENTS THE AMOUNT OF MONEY RECEIVED, THE DISPENSING IS AUTOMATICALLY STOPPED. IF THE AMOUNT OF FLUID DISPENSED IS LESS THAN THE AMOUNT OF MONEY DEPOSITED, THE CUSTOMER MAY OPERATE A CIRCUIT TO RECEIVE THE PROPER AMOUNT OF CHANGE. AS THE CHANGE IS GIVEN, THE STORED INFORMATION SIGNALS ARE REDUCED UNTIL NO INFORMATION SIGNALS REMAIN, AT WHICH TIME NO FURTHER CHANGE IS PROVIDED.

United States Patent 2,573,112 10/1951 Schneckenburger Albert F. Romanowski Greeneville;

Larry A. May, Jonesboro; Norman W. Hays, Telford, Tenn.

Jan. 17, 1969 June 28, 1971 Bowser, lnc.

Inventors Appl. No. Filed Patented Assignee FLUID PUMP HAVING PULSING MEANS AND 2,679,308 5/1954 Mooreetal.

ABSTRACT: A control and change making device is provided for a fluid dispensing pump to receive money deposited by a customer and store information signals indicative of the amount of money received. As fluid is dispensed, pulses are produced to reduce the amount of stored information signals until the desired amount of fluid is dispensed. When the amount of fluid dispensed represents the amount of money received, the dispensing is automatically stopped. If the amount of fluid dispensed is less than the amount of money deposited, the customer may operate a circuit to receive the proper amount of change. As the change is given, the stored information signals are reduced until no information signals remain, at which time no further change is provided.

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* sum 15 or 15 FT?? F" I G i3b F- Iii-3c INVENTORS ALBERT F. ROMANOWSKI LARRY A. MAY NORMAN w. HAYS BY i TTORNE S FLUID PUMP HAVING PULSING MEANS AND MONEY ACCUMULATOR BACKGROUND OF THE INVENTION Our invention relates to a control and change making device, and particularly to such a device for self-service gasoline dispensing pumps.

Monetary operated or monetary controlled dispensing pump arrangements are known in the art, such as exemplified by U.S. Pat. No. 3,360,094 granted Dec. 26, l967. While such arrangements are satisfactory, we have found that customers frequently deposit more money into the apparatus than necessary. This results either from the fact that the customer does not have the proper change to purchase the desired amount of gasoline, or from the fact that the customer's gasoline tank may not hold as much gasoline as represented by the amount of money deposited. In either case, where such devices are used, it is desirable, and in some cases essential, that apparatus be provided so that the proper amount of change can be auto matically and accurately supplied to the customer.

Accordingly, an object of our invention is to provide a new and improved control and change making device, particularly for gasoline dispensing pumps.

Another object of our invention is to provide an improved control and change making device that receives money, that permits the desired amount of gasoline to be accurately dispensed by the customer, and that then returns the proper amount of change to the customer.

Another object of our invention is to provide an improved control and change making device that dispenses gasoline at two selected rates of flow, the last rate being a slower one so that the fluid dispensing can be accurately cutoff to provide the customer with the proper amount of gasoline.

While our device is useful in self-service gasoline stations, operators prefer that the device not be used as a change making machine. Such change making machines are frequently abused by the public, and do not sell gasoline for the operator.

Accordingly, another object of our invention is to provide an improved change making device for gasoline dispensing pumps which requires any selected minimum amount of gasoline to be dispensed before the device will provide change back to the customer.

In addition to the above desirable features, operators frequently sell various grades of gasoline. Where two or more grades of gasoline are dispensed, it is desirable that the control and change making device be usable with all of such grades of gasoline.

Accordingly, another object of our invention is to provide an improved control and change making device that can be selectively used with one of a plurality of gasoline dispensing pumps.

SUMMARY OF THE INVENTION Briefly, these and other objects are achieved in accordance with our invention in connection with a gasoline dispensing pump which has means for producing pulses as a function of the monetary amount of gasoline dispensed by the pump. The device has means for receiving money and producing information signals as a function of the amount of money received. These information signals are applied to the input of an accumulator which stores infonnation signals as a function of the money received. A money counter is coupled to the pulse producing means of a dispensing pump. A selectively operable pulse circuit is also coupled to the money counter. Means are provided to couple the money counter output to the accumulator input to reduce the information signals stored in the accumulator as a function of pulses supplied to the money counter either from the dispensing pump or from the pulse circuit. When the number of pulses supplied to the money counter represents the amount of money supplied to the money receiving means, the accumulator produces a signal that stops the dispensing. Or, if the accumulator still retains stored information signals after the desired amount of fluid has been dispensed, change may be provided by operating the pulse circuit to produce pulses to reduce the number of information signals in the accumulator to zero. As this takes place, change is supplied to provide the difference between the amount of money deposited and the monetary value of fuel dispensed.

BRIEF DESCRIPTION OF THE DRAWING The subject matter which we regard as our invention is particularly pointed out and distinctly claimed in the claims. The structure and operation of our invention, together with further objects and advantages, may be better understood from the following description given in connection with the accompanying drawing, in which:

FIG. I is an elevation view of two gasoline dispensing pumps and a control and change making device in accordance with our invention;

FIG. 2 is a simplified block diagram of our control and change making device in accordance with our invention;

FIGS. 30 through 31' show a schematic diagram of a preferred embodiment of our control and change making device in accordance with our invention; and

FIGS. 30 through 3i show a schematic diagram of a preferred embodiment of our control and change making device in accordance with our invention; and

FIG. 4 shows a diagram illustrating how FIGS. 30 through 31' are to be arranged together to form a complete diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENT General In FIG. I, we have shown a view of a gasoline station embodying our invention. In the gasoline station shown, we have assumed that our control and change making device is positioned in a central housing 10 that is located conveniently, such as between a regular gasoline pump 11 and a premium or high test gasoline pump 12. Our control and change making device is intended to becompletely automatic and operable by a customer, so that the housing 10 is provided with a number of lights and fixtures. The housing 10 is provided with a vending light 14 that indicates that one ofthe pumps I 1, I2 is ready for or is in operation. The housing 10 also includes a deposit light 15 which indicates that our control and change making device will accept money for deposit. An out-of-change light 16 is provided to indicate to a customer that the control and change making device does not have sufficient change to return money to a customer, and thus warn the customer not to deposit money in excess of what his tank will hold. A change due light I7 is provided to remind a customer and the operator that change is due. We provide a return change button I9 to initiate return of change. An automatic-manual switch 20 is provided so that the pumps II, 12 can be operated manually in a typical fashion, or can be operated automatically by a customer. The housing I0 also includes slots or openings for accepting various coins, and in this case we have assumed that only 25 cent pieces, 50 cent pieces, and l dollar bills can be deposited. A change return slot or opening 2] is provided for the customer to receive any change that may be due him.

A control and change making device 23 in accordance with our invention is mounted within the housing I0, and is connected by suitable electrical lines or conduits, indicated by the dashed lines, to the pumps II, 12. The regular pump 11 has a motor and pump 24 suitably positioned for pumping gasoline from a tank to a meter 25. The meter 25 is provided with suitable gears or other connections to provide gallons and money indications at windows 26, and also to provide electrical pulses at a rate indicative of the rate of dispensing of gasoline. Preferably, the meter 25 and associated read out device is arranged to produce one electrical pulse or one electrical circuit closure for each I cent of gasoline dispensed. The output from the meter 25 is supplied to a main pipe 27 which leads through a solenoid control valve 28 to an output pipe 29. The output pipe 29 goes to a suitable hose 30 and nozzle 31 which are positioned on the outside of the pump 11. Typically. the handle of the nonle 31 rests on a handle switch 32 which can be operated after nozzle 31 is removed. Again with reference to the main pipe 27 and the output pipe 29, a smaller or slow delivery pipe 33 is shunted around the solenoid control valve 28 through its own solenoid control valve 34. The smaller or slow delivery pipe 33 is provided so that when the delivery for a particular amount of deposit is almost complete, delivery of gasoline can take place only through the smaller pipe 33 at a relatively slow rate. Thus, when the amount of gasoline dispensed equals the amount of money deposited, the small rate of gasoline flow is quickly and accurately cutoff by the solenoid control valve 34. This assures the customer that he gets the full amount of gasoline paid for, and also insures the operator that the customer does not get gasoline not paid for.

The premium pump 12 is similar in construction and arrangement to the regular pump 11, and has the same features and devices mentioned in connection with the regular pump 11. These devices and features are shown with the same reference numerals followed by a prime. Hence, a description of these devices will not be given.

in H6. 2, we have shown a simplified block diagram of our control and change making device 23 of FIG. 1. The device 23 includes a control circuit 37 which controls the operation and function of the regular and premium pumps l1, 12. The control circuit 37 is also connected to a pulse and dispenser circuit 38. The pulse and dispenser circuit 38 is also connected to the regular and premium pumps 11, 12 for receiving pulses or circuit operations indicative of dispensing. The pulse and dispenser circuit 38 is connected to a change circuit 39 which provides change to the customer after gasoline has been dispensed, and if change is due. The change circuit 39 is connected to an accumulator 40. The accumulator 40 is an important part of our control and change making device 23. The accumulator 40 provides means for storing information indicative of the amount of money deposited by a customer and reducing this stored information in response to pulses produced by the regular or premium pumps 11, 12. After gasoline has been dispensed, if there is any information still stored in the accumulator 40, then the pulse and dispense circuit 38 can be operated by the customer to cause the change circuit 39 to provide the customer with change. Simultaneously, pulses from the pulse and dispenser circuit 38 reduce the information stored in the accumulator 40 as change is returned, so that when the accumulator 40 has no further information stored, then no more change is returned to the customer. Thus, our control and change making device permits a gasoline station to be operated without an attendant, so that a customer can deposit money, dispense his own gasoline, and then get whatever change is due.

Detailed With reference to FIGS. 30 through 3i, we have shown a complete schematic diagram of our control and change making device. Because of its relatively large size and complexity, the diagram had to be placed on a number of sheets, which should be arranged in the manner indicated in FIG. 4 so that the circuit elements and leads on each sheet can be considered connected to circuit elements and leads on other sheets. Our control and change making circuit is provided with a suitable source of electrical voltage, such as l volts, 60-cycle alternating current. This alternating current is used for many ofthe circuit functions, but direct current is also required. The direct current is supplied by a transformer T1 whose secondary is connected to a full wave bridge rectifier 50. The output of the rectifier S0 is filtered by a suitable filter capacitor C1 to provide positive direct current voltage B+ on a positive bus 51, and negative direct current voltage B- on a negative bus 52. Our control and change making circuit utilizes a plurality of relays, designated by the letter R followed by a number. The relays have a number of associated contacts which are designated by the relay number followed by a dash and another number indicating the particular contact number. The relays used in the control and change making circuit are as follows:

Description Contact Nos.

Relay No;

R1 Out of change 4 R2. Regular (premium lockout) 1, 3, 4 R3. Premium (regular l0ckout).... 1, 2,3, 4 R4. Buiier for B19, slow dispense 1, 2, 3,4 R5. Handle switch operated 2, 3,4 R6. Bufier for R17, last dispense. 4 R7. Add one dollar 4 R9. Dispense count relay 4 R10. Change circuit operating 1, 3, 4 R11. Pulse relay (tor out-oi-chan 3, 4 R12. Product delivered. 3 R13. Change operate-.. 1,2,3 R14. Even nickel operat 1, 2, 4 R15. Even quarter operat 2,1,4 R16. Pulse relay (for change 1, 4 R17 Solenoid control, fast 1, 2 R18 Limit lockout for maximum deposit.. 1 R19 Solenoid control, slow 1, 2 R21 1;! transfer..-.. R22 5e transier..-. 4 R23 25 transfer... 4 R24. Add50.... 1 R25 Add 25 1 FIGS. 3a through 31', the relay contacts are shown in their position when their respective relay winding is deenergized. Thus, for example, the relay contacts R2-l are open when the relay R2 is deenergized, and the relay contacts R24 are closed when the relay R2 is deenergized. When the relay R2 is energized, the contacts R2-1 close, and the contacts R2-4 open.

Our control and change making circuit utilizes two free running or astable multivibrators 53, 54. We prefer to use two multivibrators, since they have different functions that are not necessarily required at the same time. However, with appropriate modifications, one multivibrator could suffice. The multivibrator 53 comprises two NPN transistors Q2, Q3 connected in free running fashion and connected to an output or driver transistor Q1, also an NPN type. Similarly, the multivibrator 54 comprises two NPN transistors Q4 and Q5 connected in astable or free running fashion and connected to an output or driver transistor Q6, also an NPN type. We have found that the multivibrators preferably operate or produce output pulses at the rate of around 60 pulses per minute, or 1 pulse per second. However, as will be appreciated, other rates of operation may also be utilized.

The accumulator 40 comprises a number of flip-flops, which may be either all electronic, or which may use electromagnetic relays. These flip-flops have a set input terminal S, a reset input terminal R, and a supply terminal L. Each of the upper flip-flops FFl through FF16 have an output terminal 0 which produces a positive voltage or signal whenever the respective flip-flop is in the set condition. The flip-flops have various associated contacts indicated by the flip-flop number followed by a hyphen, and followed by a contact number. These contacts are either opened or closed, depending upon the set or reset condition of the flip-flop. The contacts are shown in their condition when a flip-flop is reset. Thus, with respect to the flip-flop FFl, the contacts 1-1 and 1-2 are closed and the contacts l-3 and 1-4 are open when the flip-flop FFl is reset. When the flip-flop FF 1 is set, the contacts l-l and 1-2 open, and the contacts 1-3 and 14 close.

The detailed operation of our control and change making circuit shown in FIGS. 30 through 3i will be discussed in three parts. The first part will explain the manual operation, the second part will explain the automatic and change making operation, and the third part will give examples of the automatic and change making operation.

Manual Operation With reference to FIG. 1 as well as FIGS. 3a through 31', we have assumed that a filling station operator is on duty, and that he is able to dispense gasoline to customers and receive payment for the gasoline. In such a situation, the operator places the switch 20 on the housing in the manual position. The switch could be installed in a remote location if desired. This connects one side of the 1 volt source directly to the necessary circuit elements so that either the regular pump 11 or the premium pump 12 can be used. For example, assume that the customer wishes to purchase regular gasoline. When the operator is ready to dispense the gasoline, he removes the nozzle 31 and operates switch 32. With reference to FIGS. 30 through 31', this causes the handle switch 32 to close its three contacts. The upper contacts energize the regular dispenser motor and pump 24, and the middle contacts energize the regular dispenser solenoid 28 to that gasoline can be dispensed at a rapid rate. The lower contacts of the switch 32 are not energized, since the slow dispensing solenoid 34 is not needed for manual operation. Similarly, if gasoline is to be dispensed from the premium pump 12, the operator can remove the nozzle 31' and operate the handle switch 32. This energizes the premium dispenser motor and pump 24 through the upper contacts of the switch 32, and energizes the premium dispenser solenoid 28 through the center contacts of switch 32'. Thus, premium gasoline can be dispensed as rapidly as desired.

It will be seen that in manual operation, our control and change making circuit is not utilized. However, our control and change making circuit is compatible with a plurality of dispensers, and permits the dispensers to be used in the conventional fashion, either individually or together.

Automatic Operation If it is desired to use the control and change making device in accordance with our invention, then the operator can operate the switch to the automatic position, as shown in FIG. 1 and FIGS. 30 through 3i. The switch 20 is shown in its automatic position, and this permits the device of our invention to be used by a customer who can deposit money, dispense his own gasoline, and receive change if such change is due. With the switch 20 in the automatic position, assume that a customer wishes to deposit money and dispense gasoline, for example regular gasoline. It has been assumed that quarters, half dollars, and 1 dollar bills can be deposited for purchase. With the circuit in operation, a capacitor C2 is charged from the positive bus 51 through the cent add or deposit switch to the negative bus 52. Likewise, a capacitor C3 is charged from the positive bus 51 through the 50 cent add or deposit switch to the negative bus 52. And, a capacitor C4 is charged from the positive bus 51 through the closed relay contacts R7-4 to the negative bus 52. Each time that a quarter is deposited, the 25 cent switch is moved downward and the capacitor C2 discharges through the 25 cent relay R25. This causes the contacts R25-1 to close and supply a positive pulse through the contacts l-l to the set input terminal S of the flip-flop FFl. Likewise, when a half dollar is deposited, the capacitor C3 discharges through the 50'cent relay R24. This closes the contacts R24-1 to supply a positive pulse through the contacts 2-1 to the set input terminal of the flip-flop FFZ. And when a dollar bill is deposited, the relay R7 is energized to discharge the capacitor C4 through the upper contacts R7-4 and supply a positive pulse through the contacts 4-1 to the set input terminal S of the flip-flop FF4. Thus, a deposit of 25 cents causes the flip-flop FF1 to become set, a deposit of 50 cents causes the flip-flop F F2 to become set, and a deposit of 1 dollar causes the flip-flop FF4 to become set. Persons skilled in the art will appreciate that if a previous deposit has been made, a subsequent deposit may cause a flipflop to be reset and another flip-flop to be set. The capacitors C2, C3, and C4 allow only 1 pulse per switch closure to be produced, thus eliminating the possibility that continuous credit would be provided if one of the switches were to remain closed for some reason.

However, because of the storage capacity of the flip-flops FFl through FF16, we place a limit on the amount that can be deposited. This limit is set by the flip-flop contacts 16-5 and 8-5 connected in series, and by one of the three flip-flop contacts 1-5, 2-5, or 4-5 connected in parallel with each other and in series with the contacts 16-5 and 8-5 and the relay R18. When the flip-flops FF16 and FF8 are set, representing a deposit of 6 dollars, then if any one of the flip-flops FF 1, FFZ, or FF4 become set (representing either 25 cents, 50 cents, or 1 dollar), then the relay R18 becomes energized. When the relay R18 is energized, its contacts R18-1 open and deenergize the 1 dollar, 50 cents, and 25 cent relays or solenoids, and also deenergizes the deposit light 15. When the light 15 is extinguished, a customer is warned that he should deposit no more money. However, if the customer does deposit more money, deenergization of the 1 dollar, 50 cent, and 25 cent relays or solenoids can operate appropriate devices so that any money deposited will be returned. Also in series with the contacts R18-1 are the contacts R5-4. The relay R5 is energized if either of the handle switches 32, 32' is energized so that deposit may not be made if one of the handle switches 32, 32 is operated. The contacts RIO-1 will be opened if the change circuit operating relay R10 is energized. Thus, if the change circuit is dispensing change back to a customer, deposits may not be made, since such deposits would disrupt the change circuit operation.

When a deposit is received, one of the flip-flops FFl through F F16 causes its output terminal 0 to become positive and energize the relay R17, and also energize the relay R19. As will be explained, the relay R17 remains energized until only 5 cents credit remains in the accumulator. When the credit is reduced to 5 cents by dispensing gasoline, the relay R17 becomes deenergized. Then, only the relay R19 remains energized so that dispensing takes place at a slower rate.

Assuming that a deposit has been made, then a customer may proceed to dispense gasoline. If the customer wishes regular gasoline, he can remove the regular nozzle 31 and operate switch 32 to cause its three contacts to close. The upper contact energizes the regular dispenser motor and pump 24. This upper contact also energizes the regular relay R2 through the contacts R3-l. With the relay R2 energized, its contacts R2-4 open so that the premium relay R3 can not be energized. Voltage from the lower contacts of the switch 20 is supplied through the now closed contacts R6-4. The relay R6 was energized by the contacts R17-1 closing when the relay R17 was energized. This voltage is applied through the closed contacts R10-3 and the closed left-hand contacts R3-2 to energize the middle contacts of the switch 32. This permits the regular solenoid 28 to be operated to that gasoline may be dispensed at a rapid rate. This same voltage from the lower contacts of the switch 20 is applied through the contacts R4-1 which are closed by energization of the relay R4. The relay R4 is energized by the contacts R19-1 which are closed by energization of the relay R19. This voltage is supplied through the closed contacts R10-4 and the upper contacts R3-3 to the lower terminal of the handle switch 32 so that the solenoid 34 is also energized. Thus, with reference to H6. 1, both solenoid valves 28, 34 are energized and opened so that dispensing of regular gasoline can take place as rapidly as the customer desires. Also, the relay R5 is energized through the contacts R2-1.

However, if the customer wishes to dispense premium gasoline, then he would remove the premium nozzle 31' and would operate the premium handle switch 32'. the upper contacts of the switch 32' would energize the premium dispenser motor and pump 24'. These upper contacts would also energize the premium relay R3 through the contacts R2-4. With the relay R3 energized, its contacts R3-1 open so that the regular relay R2 can not be energized. The contacts R3-2 switch so that the right-hand contact is closed to energize the middle contacts of the switch 32; and the contacts R3-3 are operated so that the lower contacts R3-3 are closed to energize the lower contacts of the switch 32'. Thus, the premium fast solenoid 28' and the premium slow solenoid 34 are energized. Also, the relay R5 is energized through the contacts R3-1.

As previously mentioned, if at least 5 cents remains stored in the flip-flops FF1 through FF16, the relay R17 is energized,

and this energizes its buffer relay R6. With the relay R6 ener gized. its contacts R6-4 are closed so that gasoline may be dispensed from the regular pump 11 or the premium pump 12 at a rapid rate. Also, if any information remains stored in the flip-flops FFI through FF16, the relay R19 remains energized. This causes its contacts R19-1 to close and energize the buffer relay R4. With the relay R4 energized, its contacts R4-1 supply voltage to either the lower contact of the handle switch 32 or the lower contactof the handle switch 32' to energize the slow solenoid 34 or the slow solenoid 34'.

As gasoline is dispensed from the regular pump 11, the regular meter and associated readout device causes the switch 25 to close once for each 1 cent of regular gasoline dispensed. As gasoline is dispensed from the premium pump 12, the premium meter and associated readout device causes the switch 25' to close once for each 1 cent of premium gasoline dispensed. Depending upon whether regular or premium gasoline is dispensed, the relay contacts R2-3 will be operated so that one of the two switches 25, 25' will energize the relay R9. The relay R9 has a set of associated contacts R9-4 connected at the positive bus 51 to produce positive dispense pulses through the closed contacts R4-4 (as long as the relay R4 and the relay R19 are energized) and through the normally closed contacts R13-3 (closed unless the change operate relay R13 is energized) to the 1 cent data bus. This 1 cent data bus is connected through relay contacts R19-2 and the contacts 4 -l to the flip-flop FFl c'. Thus, for each 1 cent of gasoline dispensed, a pulse or information signal is applied to the flipflop FF1.

The flip-flops FFA, FF1, FF2, FF4, FFSt', FF10, and FFZU are connected as a delay and counter so as to produce a pulse for each 5 cents counted, and also for each 25 cents counted. The flip-flops are arranged so that at the beginning of a cycle of operation, the flip-flops FFA, FFle, FF2, FF4, FF10, and FF20 are in the reset condition, and so that the flip-flop FF5 is in the set condition. This is indicated by the reset button circuit which is connected to the reset input terminal R for all flip-flops but the flip-flop FFS. Set out below is a truth table indicating the conditions of the flip-flops at the start, and for 25 input pulses at the relay contacts R19-2. In this table, a indicates that the flip-flop is reset, and a 1 indicates that the flip-flop is set. A cent data pulse is produced on the 5 cent data bus at the 5th pulse, the th pulse, the th pulse, the 20th pulse, and the th pulse. At the 25th pulse, the condition is the same as it was at the start, and the cycle is repeated. Also, a 25 cent pulse is produced for supplying to the accumulator flip-flop FFl at the 20th pulse, and a 25 cent data pulse is produced on the 25 cent data bus at the 25th pulse.

the end of 20 pulses, and each 25 pulses thereafter. Also, the counter flip-flops FF1 through FF20 produce a 5 cent pulse at the end ofeach 5 input pulses.

If a customer has dispensed at least 5 cents worth of gasoline, then one pulse will have been produced on the 5 cent data bus. This pulse is coupled through the diode D3 to the product delivered relay R12. This pulse is sufficiently long to energize the relay R12 through the now closed contacts R4-3 connected to the negative bus 52. This momentary energization of the relay R12 closes its contacts R12-l so that it becomes sealed in until the contacts R4-3 open again. This arrangement is desirable so that customers will not use our device simply as a means of obtaining change, but requires the customer to insert money and actually dispense gasoline (any suitable amount) before they can get change. Before the customer can get change, he must replace the nozzles 31, 31' so that the handle switches 32, 32' are in the off position. This deenergizes the relay R5 so that its contacts R5-3 can close. If gasoline has been dispensed, the change due light 17 will be i1- luminated, to indicate to the customer that he must obtain his change. The change due light 17 is illuminated through the now closed contacts R12-3, the now closed contacts R5-2, and the intermittently closing contacts R11-3. The contacts R11-3 operate intermittently because the multivibrator 53 is energized from the positive bus 51, connected to the transistors Q1, Q2, 03, through the diode D2, through the now closed contacts R5-3, through the now closed contacts R4-2, and through the three serially connected out-of-change switches labeled 1 cent, 5 cents, and 25 cents to the negative bus 52. These out-of-change switches are normally closed unless, as will be explained, there is sufficient change left in our device. This causes the relay R11 to be intermittently energized, and thus causes its associated contacts to be intermittently opened and closed. Hence, the change due light 17 flashes on and off to tell the customer that he should obtain his change. In order to obtain change, there must, as pointed out above, be change in the device as indicated by the out-ofchange switches being closed. This applies the negative bus 52 to the start line. The relay R4 must be energized by its relay R19 and contacts R19-l, a condition that will take place only if credit remains in the accumulator. Thus, the negative bus is connected to the contacts R5-3. In order to obtain change, the customer momentarily depresses the change switch 19 to connect the negative bus to the now closed contacts R12-2. This permits the positive bus 51 to be connected through the relay R13 to the negative bus and energizes the relay R13. The relay R13 seals in through its contacts R13-1 which are connected through the now closed contacts R4-3 to the negative bus 52 so that the relay R13 remains energized after the change button 19 is released.

FF 1 FF 2e FF 4e FF 5e FF 10 FF 20 FFA Function 0 U 0 1 0 0 0 1 U 0 1 0 0 0 0 1 U 1 0 0 0 l 1 U l 0 U U U U l l U U 0 u u u U 1 U 0 5 data pulse. 1 1 u u u 1 0 U U 1 U U 1 U U I 1 U U 1 U U n U l U 1 U U n u u 1 l U 0 5e data pulse. 1 n U l 1 0 U U 1 U 1 1 0 U l l U 1 1 O U U U l l 1 U 0 u u u u U 1 0 5,.- data pulse. 1 1 U U U U 1 0 U 1 U 0 0 l 0 1 l u U U 1 0 u u l u U 1 0 55 data pulse. 1 U U U U 0 1 [25 pulse to accumulator. 2 1 u u u U U 1 U l U u u U 1 1 l u 0 U 0 1 O U 1 U U U 1 U U 1 0 O 0 {573 data pulse. 1

25 data pulse. 1

1 These pulses are used only in giving change. 2 This pulse 15 used in dispensing and giving change.

Thus, the counter flip-flops FFIE through FF20 produce a 25 cent countdown pulse to the accumulator flip-flop FFl at When the relay R13 is energized, the change making process is initiated and continues until no credit remains in the 

